Washington, DC - The US Senate Intelligence Committee's report on secret interrogations and torture of suspects by the CIA from 2001-2007 provides enough new information to justify reopening criminal investigations, rights advocates say.

The report, released Tuesday after a three-year congressional investigation, summarises classified CIA cables that described the treatment by Central Intelligence Agency operatives of 119 people captured by the United States and subjected to "enhanced interrogation" authorised by the George W Bush administration after the September 11, 2001 attacks.

"The attorney general should appoint an independent prosecutor to do a top-to-bottom investigation that goes from the White House officials who ordered these activities to people in the field who carried them out," said Chris Anders, senior legislative counsel for the American Civil Liberties Union.

The report found the CIA's tactics "were far more brutal than the CIA represented to policymakers and the American public". The CIA interrogation programme was investigated by the US Department of Justice beginning in 2009, as the Senate committee began its inquiry, but no charges were brought against officials or agents.

It's devastating. The brutality is put out in graphic detail that makes it clear the United States was going medieval on some people.

- Reed Brody, Human Rights Watch

Senate investigators concluded CIA agents used coercive interrogation techniques that had not been approved by the justice department or authorised by headquarters. Further, CIA officials actively sought to mislead Congress, the White House, the DoJ and the inspector general.

'Going medieval'

"It's devastating. The brutality is put out in graphic detail that makes it clear the United States was going medieval on some people," said Reed Brody, a counsel to Human Rights Watch and former UN investigator of atrocities. "This is more than we knew."

Senate investigators, who reviewed thousands of internal CIA documents, focused on 20 specific cases of interrogation the CIA had claimed led to useful intelligence in the US campaign against al-Qaeda. The committee argues, however, the coercive interrogations did not provide intelligence about imminent threats, nor did the methods yield useful information for counterterrorism operations.

In one instance, a prisoner at an unsupervised, secret location code-named "Cobalt" in the report, died of apparent hypothermia after being chained and left naked on a cold concrete floor overnight.

In many cases, the most aggressive coercive interrogation techniques, including extended sleep deprivation and forced stress positions - such as standing with hands shackled above heads, or being locked inside boxes - were used in combination and non-stop for days, according to the report.

"Normally when it is found out that your agents engaged in torture, the response is to prosecute," Brody told Al Jazeera. "These are crimes."

At one detention facility, prisoners were isolated, shackled in a dungeon in complete darkness with loud noise and only a bucket to use for human waste, the report said. Prisoners were hooded and dragged naked up and down corridors while being slapped and punched.

Water torture

Waterboarding of prisoners, a technique that simulates drowning by pouring water down their throats, was more harmful than the CIA had represented to Congress and the White House, leading to vomiting and convulsions, according to the report.

Saudi national Abu Zubaydah [AP]

Abu Zubaydah, a Saudi national held in secret CIA sites overseas for four years, was waterboarded for two-and-half hours the first time. He was chained naked to a wall, slapped, confined in stress positions, subjected to noise and sleep deprivation, in addition to being waterboarded for 17 consecutive days.

After one waterboarding session, Zubaydah became "completely unresponsive with bubbles rising through his open mouth" until he was revived by medics, the report said.

During CIA interrogations, Khalid Sheikh Mohammed, the alleged 9/11 mastermind, was waterboarded 183 times in one year, 2003. A medical officer wrote: "We are basically doing a series of near drownings," the report said.

Several CIA detainees were subjected to "rectal feeding" or "rectal hydration" without a documented medical need, it said.

"It is hard to read through this report and believe that there hasn't been anybody charged in these crimes," Anders told Al Jazeera.

'We tortured some folks'

In 2008, the Department of Justice appointed federal prosecutor John Durham to investigate the CIA's destruction of videos documenting waterboarding and other coercive interrogations. Durham's charter was expanded by Attorney General Eric Holder in 2009 to investigate the legality of the CIA's interrogation methods. Durham quietly concluded his work in 2012 with the closureof investigations into the deaths of two detainees.

President Barack Obama assured the CIA in 2009 that officers and agents involved in the interrogation programme would not be prosecuted so long as they had complied with justice department guidance.

"This is a time for reflection, not retribution," Obama said in a statement at the time. Earlier this year, Obama acknowledged in a press conference: "We tortured some folks."

Some legal analysts dispute the findings and premise of the Senate report - that the CIA engaged in torture.

"The US has never sanctioned torture. The techniques we used were not torture. None of them constitute torture, including waterboarding," said Jeffrey Addicott, a law professor at St Mary's University School of Law in San Antonio, Texas, and director of its Centre for Terrorism Law.

"We never engaged in torture," Addicott, a former legal adviser to US Special Forces, told Al Jazeera. "If you are here to say it's torture, then prosecute people. They haven't."

Senator John McCain, a senior Republican who suffered torture as a former prisoner of war in Vietnam, said he had objected in briefings with former Vice President Dick Cheney and former CIA Director Michael Hayden.

"I said to both that it's absolutely wrong and we should not do it. I adamantly opposed it and I spoke up against it and we passed legislation of mine through the Defence Appropriations bill that prohibits it," McCain told Al Jazeera.

'Reckless' report release

Cheney said in a US television appearance on Sunday the use of torture was appropriate and necessary after the September 11 attacks, an argument McCain rejects.

"There is no evidence that it was useful or necessary," McCain said.

With US military bases and diplomatic missions on alert for blowback from the report, Senator John Cornyn, the number two Senate Republican leader, said its release was "reckless".

"It has nothing to do with reforming intelligence or improving," Cornyn told Al Jazeera. "It has the potential to endanger not only some of our allies but also the lives and well-being of some of our intelligence operatives."

The 1949 Geneva Conventions, negotiated after World War II and ratified by the US, prohibits inhumane confinement and torture of prisoners during wartime. The 1984 United NationsConvention against Torture requires signatory states to prosecute in cases of cruel, inhumane and degrading torture or punishment.

The Senate report is a summary of the committee's enquiry and totals some 600 pages with redactions of 7 percent of its text that were negotiated with the CIA. The full report is 6,700 pages and remains classified.

"There is far more detail, all documented in the 6,700-page study," Senator Dianne Feinstein, the chairman of the Intelligence Committee, said in remarks to the Senate.

Feinstein said she hoped release of the summary "will carry the message: never again".